Question

Explain the differences between pure air ​and polluted air. [2 marks]

Answer 1

$\bullet$ The composition of pure air contains 78% nitrogen, ​ 21% oxygen and 0.03% carbon dioxide. Besides these, ​there are some other gases like methane, argon, and ​water vapour. ​[1 mark] ​
$\bullet$ The air is said to be polluted when the composition of air ​is altered by the addition of harmful substances or gases such as sulphur dioxide, carbon monoxide, nitrogen dioxide, and particulate matter.​ [1 mark]